Calculating machine



Nov. 12, 1946. J. M. LAIHO 2,410,323

CALCULATING CHINE Filed Sept. 17, 1941 13 Sheets-Sheet 1 Nov. 12, 1946. J. M. LAIHO CALCULATING MACHINE Filed Sept. 17, 1941 13 Sheets-Sheet 2 Nov. 12, 1946. J. M. LAIHO CALCULATING MACHINE 13 Sheets-Sheet 3 Filed Sept. 17, 1941 Nov. 12, 1946. J. M. LAIHO CALCULATING MACHINE Filed Sept. 17, 1941 13 Sheets-Sheet 4 INVENTOR. Jalnwf N. L ai/za BY Q/M, M Ma Nov. 12, 1946. J. M. LAIHO 2,410,823

CALCULATING MACHINE Filed Sept. 17, 1941 13 Sheets-Sheet 5 mvmox MLZFM Lazjw BY @4450, 5 gay Nov. 12, 1946. J. M. LAHHO 2,410,823

CALCULATING MACHINE Filed Sept. 17, 1941 13 Sheets-Sheet 6 BY W Nov. 12, 1946. J. M. LAIHO CALCULATING MACHINE Filed Sept. 17, 1941 13 Sheets-Sheet 7 INVENTOR. JEzZvLei M Laifza BY 69w 6? 21/ Nov. 12, 1946. J. M. LAIHO 2,410,823

CALCULATING MACHINE Filed Sept. 17, 1941 13 Sheets-Sheet 8 INVENTOR. JaZmeF/VLaz'fw BY Q/dlfm 692m, 44

Nov. 12, 1946. J. M. LAIHO CALCULATING MACHINE Filed Sept. 17, 1941 13 Sheets-Sheet 9 NOV. 12, 1946. M LAIHQ CALCULATING MACHINE Filed Sept. 17, 1941 13 Sheets-Sheet l1 Nov. 12, 1946. M. LAIHO 2,4

CALCULATING MACHINE Filed Sept. 1'7, 1941 15 Sheets-Sheet 12 INVENIOR.

Nov. 12, 1946. J, M, LAIHO CALCULATING MACHINE 13 Sheets-Sheet 13 Filed Sept. 17. 1941 Patented Nov. 12, 1946 CALCQLATIN G MACHINE Jalmer M. Laiho, Skokie, 111., assignor to Felt & Tarrant Manufacturing Company, Chicago, Ill., a corporation of Illinois Application September 17, 1941, Serial No. 411,194

40 Claims. 1

This invention relates in general to calculating machines, and has mor particular reference to the provision of means for facilitating the use of power-driven key-responsive machines in subtractive operations.

In calculating machines of the type shown in United States Letters Patent No. 2,063,962, issued December 15, 1936, and generally in substantially all machines having actuatin mechanism adapted to drive the registering or accumulating mechanism in only one direction, subtraction is performed by a process of complemental addition. For example, if it is desired to subtract 127 from the number 824, the latter is registered in the numeral wheels of the accumulator, and the nines complement of the subtrahend less one, or the tens complement of the units order and the nines complement of all other orders of the subtrahend, namely, 873 is added to the minuend. This would normally leave a result of 1697 in the accumulator. In certain of the prior art machines, such as those disclosed in the patents to D. E. Felt, Nos. 767,107 and 960,528, issued on August 9, 1904, and June 7, 1910, respectively, a subtraction or carry cut-out lever is provided in association with each denominational order of accumulator mechanism, except the units order, which is selectively operable to prevent a transfer or a carry of the s thereto. In this manner, the 10's added to the left of the highest order of the minuend in subtractive operations are eliminated. In other of the prior art machines, the carry of the "10's" is allowed to take place, and 9s are added in all orders to the left of that order in which the first figure of the subtrahend is entered, thus bringing to zero position all of the said orders. Thus, in both instances, the correct result, 697, will appear on the numeral wheels of the accumulator.

To aid the operator in quickly determining the complement of the subtrahend, it has been the practice to imprint in small figures on each key the nines complement of the larger figure imprinted thereon, as shown in Fig. 1 of the abovementioned U. S. letters Patent No. 2,063,962. In the machine of the instant invention, however, the operator is completely relieved of the responsibility and mental burden of determining the complement of the subtrahend and locating it upon the keyboard when performing a subtractive operation. This is accomplished by means of a control key which, as will be more fully explained hereafter, upon depression by the operator, conditions the machine to automatically add to the minuend the nines complement of any key subsequently depressed in any denominational order higher than the units order, and to automatically add the tens complement of the key depressed in the units order, and to add the respective complements of zero in any orders where no keys are depressed. The complemental marking of the keys is dispensed with, so there are only the large figures thereon and all chance of confusion to the operator is eliminated.

Heretofore, in machines of this type, the actuating movement was immediately responsive to depression of any ordinal key, but the present invention contemplates the provision of means for delaying the power action or actuating movement and maintaining the keys representing the subtrahend in a depressed, or key-set, position during a subtractive operation until released, the reason for which will be made evident in the descriptionfollowing. In the machine of the present invention, if it is desired to subtract 20964 from the number 45678, the latter is re stered in e m1- meral wheels of the accumulator by depression of the keys bearing those figures. The machine is then conditioned for the subtractive operation by a manual control, and the keys bearing the figures representing the subtrahend 20964 are then depressed and will be maintained in such position until a second control is manipulated, when the nines complement of the first four figures and the tens complement of the units figure will be automatically added to the minuend. In other words, while the keys bearing the figures "20964 were depressed, the amount "79036 was added to the minuend, which ordinarily would leave a result of 124714. However, while the complement of the subtrahend is being added to the minuend, 9s are also being added in all orders in which no ordinal key has been depressed, so that the correct result will be obtained. In other words, 9's are added in all orders to the left of that in which the first figure of the subtrahend occurs, in order to bring all of the higher denominational wheels to zero position through a carrying operation, thereby leaving the true remainder 24714.

The principal object of the invention, therefore, is to simplify subtractive operations in keyresponsive calculatingmachines.

Another important object of the invention is the provision of control means operable to render a normally key-responsive calculating machine key-set, for the purpose of enabling the complemental values of a subtrahend to be automatically entered in subtractive operations.

A further important object of the invention is to eliminate the complemental indicia usually employed on the ordinal keys of calculating machines having uni-directional actuating mechanism.

Another object of the invention is the provision of means for causing entry into the accumulator of a, calculating machine of the nines complements of the values of the keys depressed in all denominational orders, except the units order, and the tens complement of the value of any key depressed in the units order.

A further object of the invention is the provision in such a machine of means for also causing the automatic entry into the accumulator of 9's in all denominational orders in which no keys have been depressed, and in the units order if no key has been depressed therein.

Another object of the invention is the provision of normally inoperative subtraction control means operable to condition a key-responsive calculating machine for a subtraction operation, together with other control means operable to cause actuation of the machine and automatic return of the subtraction control means to inoperative position.

A further object of the invention is to provide means for insuring proper sequential operation of such control means.

Another object of the invention is the provision of normally inoperative subtraction control means operable to render a key-responsive calculating machine key-set and to condition the digital actuation control mechanism to cause complemental values of the keys depressed to be entered in the accumulator.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, when taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

In the drawings:

Figure 1 is a top plan view of a calculating machine embodying my invention, showing the minus and equals keys located to the left of the several denominational orders of digital keys;

Figure 2 is a longitudinal, vertical section taken through the calculating machine shown in Fig. 1 on a planeadjacent a column of digital keys;

Figure 3 is a longitudinal vertical section taken at the left side of the calculating machine shown in Fig. l, with parts omitted or broken away and also showing details of the accumulator mechanism;

Figure 4 is a longitudinal vertical section taken through the calculating machine of Fig. 1 showing details of a single order of actuating mechanism, with parts omitted;

Figures 5, 6, 7 and 8 are enlarged detail views of the subtraction control mechanism in various states of operation;

Figure 9 is a longitudinal vertical section taken through the calculating machine shown in Fig. 1 on a plane adjacent the overflow column and showing the subtraction control mechanism;

Figures 10, 11 and 12 are detail views of the digital actuation control mechanism.

Figure 13 is a detail view showing the construction of the digital control bar, taken along the line l3l3 of Fig. 11;

Figure 14 is a longitudinal vertical section taken through the calculating machine of Fig. l on a plane adjacent the overflow column and showing the digital control shifting mechanism;

Figure 15 is a transverse section taken at the rear of the machine and looking toward the front thereof, with certain parts omitted to show details of the subtraction control mechanism when the machine is set for additive actuation;

Figure 16 is a similar view showing the subtraction control mechanism when the machine is set for subtractive operation;

Figure 17 is a top plan view, broken away centrally from front to back, of the calculating machine shown in Fig. 1, showing details of the arrangement of the digital actuation control mechanism and shifting means; and

Figure 18 is a detail sectional view showing the connecting means for operating the actuating mechanism of the overflow order.

For the purpose of illustrating my invention, I have shown in the drawings a key-responsive, power-driven calculating machine similar to that shown and described in Patent No. 2,063,962, hereinbefore referred to, and with some changes as subsequently shown in United States Letters Patent No. 2,018,933 issued October 29, 1935. Referring more particularly to the drawings, the calculating machine is shown as having an outer casing 2i within which the various instrumentalities of the machine are mounted on skeleton frame members or partition plates 22 disposed between the actuating mechanisms of the several denominational orders and secured together in spaced relationship at suitable points by tie-rods 23. A plurality of columns of digital keys 20, normally held in raised position by means of springs 38, are arranged to extend through a keyboard 25, positioned as part of the upper wall of the casing 2i, which keys are adapted for manipulation to determine the digital degree of actuation to be imparted to the different denominational orders of accumulator mechanism. Each column of keys 25 controls the rotation of an accumulator actuating pinion as (Fig. 2) journaled upon a transverse shaft 2? that extends across the machine and is supported by the frame members 22. Rotation of each of the actuating pinions 26 is transmitted through an internal ratchet mechanism to a combined lantern wheel and accumulator gear 28 (Figs. 3 and 4) which is also journaled on the shaft 27. The gear of the lantern wheel 28 meshes with a carrying gear 30 journaled on a'sha-ft 2% (Figs. 3 and s), which is disposed in parallel relationship to the shaft 2'7. The carrying gear also meshes with an intermediate gear 3| journaled on a transverse shaft 32, which in turn meshes with a numeral wheel pinion 33 journaled on a transverse shaft 86 and fixed to a numeral wheel 35 (Figs. 3 and 4).

Carrying mechanism is provided in each denominational order of the accumulator mechanism for the purpose of imparting a digital unit of actuation thereto each time that a tens transfer is to take place from the next lower denominational order of the accumulator. This mechanism, as well as that hereinbefore described, is more fully disclosed in United States Letters Patent No. 1,357,747, and No. 1,357,748, issued on November 2, 1920, and includes a carrying-cam member 36 (Fig. 4), which is given a rotation by a suitable carrying motor spring 3'1! associated with a carrying gear of the next lower denominational order for each tens transfer that is to be effected. The carrying-cam member 38 acts upon a dolly roll secured to a bell-crank carrying-lever (not shown) to swing the latter in a clockwise direction, viewing Figs. 3 and 4. Such swinging oi the carrying-lever causes a carrying pawl ii pivotally mounted on said lever to throw the lantern wheel and accumulator gear 28 a sufficient distance to impart, through the train of gears, a digital unit of actuation to the numeral wheel 35.

The adding is accomplished upon depression of the keys 24 and corresponding actuation of gear sectors 42 (Fig. 4) which are in mesh with the pinions 28, a said sector being associated with each denominational section of the accumulator unit in association with its controlling column of keys. The gear sectors and the control and actuating mechanism for them are duplicated for each denominational order of the calculating machine, and a general description of a single set of such mechanism will be sufiicient for an understanding of them all, except that they have to be arranged and adapted to cooperate selectively and collectively with the power members.

The gear sectors 42 are mounted upon a shaft 43 which extends through the partition plates 22 of the machine, and are adapted to be moved downwardly (viewing Figs. 2 and 4) on an idle or setting stroke in amount determined by the value of the particular digital key 24 of the associated column depressed, this amount increasing in graduating steps from "1 to 9. The keys 24 in addition act through a power trip mechanism to efiect a connection whereby power supplied by an electric motor, indicated generally at 44 (Fig. 3) through a power shaft 45, which is connected to the motor in any suitable manner, is effective to extend a spring 48 associated with the particular order of mechanism with which the key depressed is identified. Release of this spring thereafter accomplishes adding movement in amount determined by the particular digital key of the order depressed. Upon depression of said key, the gear sector 42 is moved through its idle or downward stroke by the power shaft 45 into position to impart proper and accurate digital accumulation to the adding mechanism upon its return movement, which is accomplished by the associated spring 48.

In the calculating machine shown in the drawings, depression of a key 24 causes its stem 41 (Fig. 2) to engage a parallel motion bar 48 which is pivoted at the front at 49 and at the rear at 5| to levers 52 and '53, respectively, which levers are pivoted in turn upon cross shafts or rods 54 and 54 extending through the partition plates 22. A link 55 is pivotally connected at 56 to the lever 52 and at 51 to the lever 53. The bar 48, levers 52 and 53 and the link 55 form part of a parallel motion device, and are constructed and mounted as shown and described in United States Letters Patent No. 2,063,962, earlier mentioned. Further and more particular description of these parts is therefore thought to be unnecessary. Each of the gear sectors 42, as stated above, is pivoted upon a cross shaft 43, and through a yielding clutch 83 is articulately connected to a hook 58 by a link 59 (the hook 58 and link 59 being articulately connected to a vertical guide member 68 which in turn is pivotally mounted on a shaft 58). Each gear sector 42 is also articulately connected to a movement controllin bar, generally shown at 6|, by a pin 62 securely fixed to an arm 39 of the gear sector 42 (Fig. 4), as will be later described in detail. A spring 64 attached to lever 53 and to a tail piece 65 of a latch member 66 carried by the bar 55 normally contributes toward holding the parallel motion device in elevated position, and also holds latch member 88 in forward position for a purpose which will be presently explained. A dog 51 which is pivoted at 88 on the parallel motion bar 48 is provided with a a laterally extending lug 89, which is adapted for engagement with a 111g or shelf II on a springlifted lever 12 pivotally mounted on the guide member 60 with the hook 58. The operation of the parts is such that upon depression of a key 24, the stem 41 engages and depresses bar 48, imparting motion to the parallel motion device, which carries dog 81 downwardly to depress lever 12. A spring mounted on the pivot between the link 58 and the hook 58 engages the lever 12 and the hook to urge the rear end of the latter downwardly, so that it will normally cause engagement of the hook 58 with a toothed wheel 13 upon depression of lever 12. However, this spring connection between hook 58 and lever 12 will permit movement of the latter by the dog 81 relative to the hook, if the hook is restrained in its normal raised position of Figs. 2 and 4 in a manner to be later described. The toothed wheel 13 is fastened to the power shaft 45, which continually turns in a counter-clockwise direction. The engagement of the hook 58 with the wheel 13 pulls the link -59 toward the rear of the machine, or toward the left, viewing Figs. 2 and 4, which imparts downward motion to gear section 42, through the yielding clutch 63. Forward motion is thus imparted to the digital control bar 5|, until one of several lugs projecting vertically therefrom, as will be hereafter more fully explained, is stopped by the stem 41 of the key 24 depressed.

The rearward motion of hook 58 and link 59, which are articulately connected to each other and to guide arm 68, causes said guide arm to pivot in a counter-clockwise direction about its shaft 50 to extend spring 45, one end of which is connected to the guide arm and the other end to a shaft or rod extending through partition plates 22. The link 59 moves the gear sector 42 downwardly on an idle stroke and into position to impart an adding movement upon release of the hook 58 and contraction of the spring 48. The downward movement of the gear sector 42 is under the control of the digital control bar SI (Fig. 4), and the gear sector is halted when it has been moved downwardly the proper distance, enabling it upon return to impart the degree of digital advancement to the adding mechanism which corresponds to the particular key depressed. The yielding clutch 63 permits the continuation of the rearward movement of the link 59 after downward movement of the gear sector 42 has been stopped, and until the end of the power stroke and the automatic release of the hook 58. The release of the hook 58 is accomplished automatically in each instance, after a set increment of action has been imparted to the link 59, by the teeth of the wheel 13. Upon the 80 return stroke (the operative stroke of the gear sector), the yielding clutch 63 permits relative movement of the parts in reverse direction to the beginning of the adding movement, and thereafter the adding actuation is accomplished.

It is apparent, therefore, that upon depression of a key 24, the digital control bar 6| determines the degree and extent of the downward movement of the gear sector 42, and the bar 48 accomplishes connection of the latter to the power 70 mechanism. Means are provided to prevent return movement of the dog 61 before the hook 58 has opportunity to fully engage the toothed wheel, which means comprise latch member 88 which is pivoted at 14 on link 55. This latch member has an engaging arm 15 which is adapted to engage upon the laterally projecting end it of the dog 61 to hold the dog down against return upward movement and the parallel motion device in depressed position. Just prior to the release of the hook 58, a pin 11 in an upwardly extending arm 18 of vertical guide member 80, which through its connection with hook 58 has been carried rearwardly, engages a finger 19 of latch member 66 and frees the dog 81 so that the parallel motion device may return to normal raised position. In this operation, the key 24 which has been operated is held depressed until release of the hook 56 from the wheel 13, when the key will be released and returned to normal raised position. A bar 8| having rearwardly extending pointed locking lugs or teeth 82, is pivoted upon studs 83 and 83' extending through slots 82 and 84' in bars 58 in each denominational order of the machine. Consequently, upon depression of a key 24, bar BI is moved rearwardly (to the left viewing Fig. 2), relative to key stems 4W. Referring more particularly to Figs. 15 and 16, each key stem is provided adjacent its lower end with an aperture 85 extending therethrough into which the tooth 82 enters in the rearward movement of the bar Bl, thus holding the key down until the parallel motion device is released and the parts returned to normal elevated position. It will be understood that, while no two keys 26 of the same column or denominational order may be operated simultaneously, as described in Patent No. 2,043,021 issued June 2, 1936, any key of one order may be operated at the same time as any desired key of any other denominational order or orders.

The present invention contemplates the provision of means for facilitating subtractive operations by conditioning the machine to automatically control the digital actuation of the actuating mechanism therein in accordance with the complemental value of the keys depressed in entering the subtrahend. Such means completely eliminate the heretofore dual marking of the keys in accordance with the nines complemental value thereof, thus relieving the operator of the mental burden connected with determining the complemental value of the subtrahend. In the exemplary embodiment, after the machine is conditioned for a subtractive operation, the keys representing the figures of the subtrahend are depressed and maintained in such position, and the actuating movement is delayed until a second control key is depressed which automatically causes the complement of the depressed keys representing the subtrahend to be added to the minuend in the accumulator. Further, simultaneously with the adding of the complement of the subtrahend, 9's are added in all denominational orders in which no key has been depressed, except the units order in which "10 is added if no key therein has been depressed, for a purpose which will be more fully explained hereafter.

The subtraction control device in its preferred form comprises a set of keys including minus and "equals control keys 86 and 81, respectively, (Figs. 1, 5. 6 and '7) located to the left of the ordinal series of keys 22 for convenient access. The keys are provided with the usual stems 88 extending through the keyboard 25 and are normally held in raised position by springs 238.

The lower portion of stem 88 of "minus key 86 is in engagement with a parallel motion bar 89 which is a modified form of the parallel motion bars as earlier described. The arrangement and construction of the parallel motion bar 89 is similar to that of bar 38, so that further description thereof is not thought to be necessary, the parts of the parallel motion device 89 being given reference numerals having the last two figures the same as those given to similar parts of the bar 48, and preceded by the figure 2." Depression of minus" control key 86 and parallel motion device 89 causes forward movement (to the right viewing Figs. 5 and 6) of the link 255, and allows arm 215 of latch member 2% to engage the laterally projecting end 2% of dog 261, which is pivoted at 268 on parallel motion device 89, to hold the parallel motion device in depressed position. The key 86 is also maintained in depressed position by a tooth 9! formed on a. bar 92 which is pivoted upon studs 283 and 283' extending through slots 284i and 286' in the bar 89. Upon depression of key 86, the bar 92 is moved rearwardly (to the left viewing Figs. 5 and 6), allowing tooth 9! to enter the aperture 285 in the key stem 88. The bar 92 is also provided with a vertical projection 93 adapted normally to underlie the stem 88 of the equals key 81, for a, purpose to be later described.

As has already been mentioned, it is necessary that the actuating action be not immediately responsive to depression of the ordinal keys 2%, as is normally the case, and that the keys representing the subtrahend be maintained in a depressed position when a subtractive operation is being performed. To this end, therefore, means are provided, which are operable at the will of the operator, for preventing immediate engagement of hooks 58 with toothed wheels it upon depression of ordinal keys 2%. These means are under the control of the minus key 38 which, upon depression, engages an upwardly extending arm 94 (Figs. 7 and 8) of a lever 95 which is also provided with a downwardly and forwardly extending arm 95. The lever 95 is pivoted at 9?! on a pin fixed to an intermediate plate 22, and is normally maintained under tension of a spring 98 in its upward position, as shown in full lines in Fig. 8, where further upward movement is limited by a vertical lug formed on arm 96 contacting the under surface of the bottom plate of the keyboard 25. Engagement of stem B8 of minus control key 86 with arm 96 rocks the lever in a clockwise direction with a consequent downward movement of arm at, as shown in Fig. '7. Pivoted to the lower end of arm 95 is a pawl 98 which is provided with a downwardly extending arm 99, a rearwardly extending horizontal arm fill and an upwardly extending arm I92. The pawl is normally urged in a counterclockwise direction (viewing Figs. 7 and 8) by a spring IE3, and such movement is limited by engagement of arm fill with a pin ltd secured to the arm 96. The lower arm 95 is normally positioned above a pin H35 in an arm 505 which is securely fastened to a transverse rock shaft I01. Located upon the shaft Hill and also securely fastened thereto are lock arms H98 (Figs. 4, 5, 6 and 1'7), one for each denominational order of the machine, and each of which is provided with a laterally extending lug 109 adapted, upon depression of control key 86 and consequent counter-clockwise rotation of rock shaft it'd, to engage an associated vertical lug ill, one of which is struck up from each of the hook members 58. The lock arms Hi8 are normally held in upward disengaging position under tension of a spring it, which normally maintains shaft ill! in the full line position of Figs. 7 and 8.

It will be readily apparent, however, that depression of minus key 86 will, through arm 96 and pawl 98, cause shaft I01 to rock, allowing lugs I09 of all of the lock arms I08 to engage their respective lugs III of hooks 58. The parts are maintained in such locking engagement during subsequent depression of ordinal keys representing figures of the subtrahend, which, as previously explained, would normally result in a power action through engagement of hook 58 with toothed wheel I3, and until released by depression of the equals key 81, as will be hereafter more fully explained. As earlier described, upon depression, the ordinal keys 24 are momentarily held depressed by engagement of tooth 82 with aperture 85 until the parallel motion device 48 is allowed to rise, when pin 11 of vertical guide member 60 releases latch 66, freeing dog 61. Until engagement of the hoolm 58 with their toothed wheels I3 is allowed to take place, therefore, it will be readily understood that the keys 24 depressed in entering the subtrahend will be maintained in such key-set position until the hooks 58 are released from lock arms I08 and allowed to drop into engagement with toothed trol the digital actuation of the adding mechanism in accordance with the nines complemental value of the keys depressed in entering a subtrahend in all denominational orders except the units order, in which the tens complemental value of the key depressed is added. In other words, in performing a subtractive operation, the keys used in such calculation have only single value indicia inscribed on their top surfaces, the complemental value of such keys depressed in entering the subtrahend being automatically determined and added to the minuend by means now to be described. The mechanism controlling the digital actuation of the adding mechanism in each denominational order is indicated generally at 6| (Fig. 11) and comprises a regular stop bar I I2 and a complemental stop bar I I3, secured together and spaced relative to each other by means of studs II4 (Figs. 10 and 13). The bars H2 and I I3 have formed thereon vertically projecting stop lugs H5, the lugs I I5 of the stop bar H2 being spaced progressively further back of the key stems from the front to the rear of the machine, and the lugs H5 of stop bar H3 being spaced progressively further back of the key stems from the rear to the front of the machine (as shown in Figs. 4, 10, 11 and 14). The stop lug II5 of the regular stop bar H2 just to the rear of the 1 key is spaced one step back of the 1" key, and the distance from each succeeding stop lug to its associated key stem toward the rear of the machine graduatedly increases until the rearmost lug is spaced nine steps back of the 9" key. The stop lug of the complemental stop bar H3 just to the rear of the 1 key is spaced eight steps back of the 1 key and the spacing graduatedly decreases until the lug back of the 8 key is spaced one step therefrom and the last stop lug is just even with the 9 key.

It has been earlier explained that in machines of this type it has been the necessary practice in entering the subtrahend to enter one less in the units order, or, in other words, to strike the nines complement of all orders except the units order, in which the tens complement was entered to obtain the correct result. Means have been provided in the present invention to automatically control the digital actuation of the accumulator mechanism in the units order in accordance with the tens complement of the key depressed, or, if no key has been depressed, to automatically add 10 in such order to bring about the correct result. This is accomplished by an arrangement or spacing of the stops on the tens complemental stop bar 3' of the units order (as shown in Fig. 12), different from that of the nines complemental stop bar H3 in all other orders. In other words, the stops H5 on the tens complemental stop bar 3' of the movement controlling bar 6| in the units order (Figs. 10 and 12) are spaced progressively one step further back than are the stops H5 on the nines complemental stop bars H3. The gear sector in the units order therefore is given a relatively greater adding movement by the tens complemental stop bar H3 than are the gear sectors of all other higher denominational orders under the control of their complemental stop bars I I3. The complemental stop bars H3 and H3 are each provided at their forward ends with depending arms H6 having a bifurcated portion adapted to embrace the pin 62 located in the upwardly extending arm 39 of the associated gear sector 42 (Figs. 4 and 14). As has already been described, in normal operation, upon depression of an ordinal key 24 and engagement of the clutch hook 58 with the toothed wheel 13, there is a consequent downward movement of gear sector 42 which, through its connection with the digital control bar 6|, as just explained, is halted by engagement of the associated stop lug H5 on the stop bar H2 with the stem 41 of the depressed key. The resulting movement is thus just sufficient to add into the accumulator an amount represented by the value of the key depressed.

Means are provided, when desiring to enter the complement of the subtrahend during a subtractive operation, for shifting the complemental stop bars H3 and H3 into operative relation with the ordinal series of keys, so that upon depression of a key and subsequent downward movement of the gear sector l2, the complemental value of the key depressed will be added into the accumulator, as distinguished from the actual value of the key depressed when the regular stop bar H2 is in operative relation therewith. The lower portion of stem 88 of the subtraction control minus key 88 is provided with an angular surface in engagement with a roll H8 which is rotatably secured to an upright arm H9 (viewing Figs. 14, 15 and 16). The arm H8 is fixedly secured to a rock shaft I2I running from front to rear of the machine (Figs. 14 and 17), and having a bearing in the lateral faces I22 and I22 provided in the upper portion of vertical support pieces H1 and I H, which are in turn pivotally supported on the tie rods 23. Also securely fixed to the rock shaft I2I are upright arms I23 and I24, located adjacent the front and rear of th machine, respectively (Fig. 14). The upper free portion of the arm I23 is disposed in a small slotted portion I20 of a transverse support bar I25 positioned near the front of the machine (Figs. 10, 14 and 17), which is slidably mounted in the intermediate frame plates 22 and is provided with a plurality of laterally spaced, upstanding pins I26 fixed therein. The pins I23 are adapted to enter the open portion between the stop bars H2 and I I3 of the digital control bars 6| to maintain proper alignment thereof ll with respect to the key stems M. A similar transverse support bar I2! is mounted at the rear of the machine, and formed thereon is a forwardly extending, slightly offset horizontal arm (Figs. and 14) provided at its forward end with a small slotted portion I20, similar to the slotted portion I20 in the transverse support bar I25, in which is positioned the upper portion of the upright arm I24. The bar I21 is also provided with pins I26 adapted to be embraced by the open portion of the digital control bars ill to maintain proper alignment of the rear ends thereof with respect to the key stems 41. The rock shaft I2I and the support bars I25 and I21 and digital control bars BI are normally maintained in the position of Fig. under tension of a spring I30 interconnected between the lower end of the arm I23 and a frame plate 22 to retain the regular stop bars I I2 in operative relationship with their associated digital key stems.

With such an arrangement, it will readily be perceived that upon depression of the minus control key 86, the resulting movement of arm II9 to the left (viewing Figs. 15 and 16) will cause the shaft IZI to be rocked counter-clockwise to shift the support bars I25 and I2I to the left, through the medium of upright arms I23 and I26. Th digital control bars GI, supported by the bars I25 and I27, will similarly be shifted to position the stop bars H3 and H3 in operative relation with the stop portions I9 of the key stems 41. It will be apparent that when either of the stop bars H2 or H3 is in operative relation with the stop portion I9 of the ordinal key stem, the other stop bar is completely out of operativ relation therewith. This is accomplished by means of a slot 40 which is cut in the lower portion of each of the key stems 41 and is adapted to be in alignment with the stop bars H3 and H3 when the stop bars II 2 are in eflective or operative position relative to the key stems 41, as shown in Fig. 15. When the stop bars H3 and H3 are in effective or operative position relative to the key stems 41, then the stop bars II2 will pass freely by the stop portions I9 at the left of the key stems, as viewed in Fig. 16.

As has been previously described, the parallel motion bar 89 and minus control key 88 are maintained in depressed position after actuation of the latter, and lock arms I08, in conjunction with the vertical lugs I I I, are in position to prevent engagement of hooks 58 with the toothed wheels 13, which otherwise would result in an actuating movement upon depression of an ordinal key when entering the subtrahend in a subtractive operation. The ordinal keys depressed in entering the subtrahend are maintained in such depressed or key-set position following depression of the minus control key 86, and the parallel motion bars of the respective orders cannot return to normal because of the lateral ends of their dogs I37 having been engaged by the associated latch members 66, which remain in such engaged position until a power action takes place, as earlier described.

Means are also provided, therefore, for releasing the clutch hooks 58, after the subtrahend has been set upon the keyboard, to enable their engagement with the toothed wheels I3 to allow the complement of the subtrahend to be added into the accumulator mechanism to complete the subtractive calculation. The means for accomplishing this is under the control of the equals key 81, the stem 88 of which is in engagement with a lever I28 (Figs. 7 and 8) which is provided with a hub portion IZQ pivoted on a short shaft I 3| fixed to an intermediate frame plate 22. The lever I28 is provided adjacent its rearward end with a downwardly extending arm I32, to the lower extremity of which is securely fixed a pin i33 adapted for engagement with the upwardly extending arm I 02 of pawl 90. The pawl 98 is rocked in a clockwise direction, viewing Figs. 7 and 8, against the tension of its spring I 03, upon depression of the equals key 81. Such clockwise movement of the pawl 98 causes its lower arm 99 to be swung rearwardly to be disengaged from pin I05 of arm I06, allowing the shaft I07 to be rocked clockwise under the tension of its spring I00. The lock arms I08 are thus removed from locking engagement with the lugs III formed on the hooks 50, thereby allowing those hooks 5B in the denominational orders in which digital keys have been depressed in the previous setting of the subtrahend into the keyboard to drop into engagement with their toothed wheels 13 (Fig. 7).

As has been mentioned, it is necessary that 9s be added in all denominational orders in which no digital key has been depressed, and that 10 be added in the units order if no key has been depressed therein, for the purpose already explained. To accomplish this, the lever I28 is provided at its forward end with a second downwardly extending arm Ial provided with a bifurcated lower portion I35 embracing a pin I36 fixed in the curved upper end of a lever Isl. The lever I31 is securely fixed to a tranverse rock shaft I38 and is urged in a rearward or counterclockwise direction, viewing Figs. '7 and 8, under tension of spring I00. Also securely fixed to the rock shaft I38 are a plurality of upright arms I39, spaced transversely across the machine in each denominational order thereof, the upper extremities of said arms being in engageable relationship with pins I4I in links 55 (Fig. 2). Depression of the equals" key 81, as has already been described, rocks lever l28 upon its pivot, thus swinging its forward arm I36 upwardly to rock the shaft I38 forwardly. Such movement also swings all of the arms I30 forwardly, thereby urging the links 55 in a forward direction. Movement of any of the links 55 in this manner imparts motion to the associated parallel motion device to cause depression of the hook 58 controlled thereby into the path of its associated toothed wheel I3, which results in an adding actuation in that denominational order. Movement of the parallel motion device not having resulted from depression of a digital key 26 in such order, it will be readily apparent that bar 6| which controls the digital setting of the gear sector 42 will receive full forward movement, with a consequent maximum downward movement of the gear sector sufilcient to add 9 into the accumulator upon the upstroke of the sector under tension of spring 4t. When no key has been depressed in the units order, that is, when a zero occurs in the units order of the subtrahend, forward swinging of the arm I39 therein will likewise cause maximum downward movement of the gear sector 62, but the resultant upstroke by the spring 15 will add 10 into the units order of the accumulator, rather than the 9's added in the other orders in which no keys were depressed.

In machines in which the present invention is embodied, there is usually provided an overflow numeral wheel I50 (Fig. 1) to which is transferred the carry of the 10s resulting from operation of the actuating mechanism in the last or highest denominational order. Formerly, in such machines, a subtraction or carry cutout lever was provided in association with each denominational order of accumulator mechanism which was selectively operable to prevent a transfer or a carry of the 10s thereto from a lower denominational order. The present invention, however, contemplates the provision of actuating mechanism in the overflow order for automatically adding the value of 9 to the accumulator mechanism of that order to bring to zero position the numeral wheel of that order when a 1 has been carried thereto by the entering of the complemental value of the subtrahend and the subsequent carrying of the 9s across the register as just described. To this end there is provided a sector 242 (Fig. 9) similar to the sectors 42 already described and mounted on the shaft 43, but directly connected to the guide member 280 by means of a link 259, which is pivotally connected to the sector 242 at I42 and to guide member 260 at I43. A spring 246 connected at I44 to guide member 268 and to a rod extending through the intermediate frame plates 22 at I45 normally serves to maintain the guide member 260 and gear sector 242 in the position of Fig. 9. Rearward movement of the guide member 260 will, through the link connection 259, cause the actuating sector 242, to be moved downwardly in its idle or setting stroke, and spring 246 will return it to normal raised position in an adding movement in the manner previously explained, relative to the regular sectors 42.

Rearward movement of the guide member 260 in the overflow order is accomplished through connection with the guide member 80 of the next lower denominational order, or that order to the right (viewing Figs. 1 and 18) of the overflow order. Upon forward movement of link 255 when parallel motion bar 89 is depressed by minus control key 86, a pin I46 fixed to the link 255 urges forwardly an upright arm I41 with which it is normally in engagement (Figs. 5, 6 and 9). The upright arm I41 is part of a lever I48 mounted upon a short shaft I49 and urged in a counter-clockwise direction under tension of a spring II (Fig. 5). The lever I48 is also provided with a downwardly and forwardly extending arm I52 in the forward extremity of which is located a pin I53 in engagement with the upper surface of a lock piece I54. The lock piece I54 is pivotally secured at I55 to a horizontal arm I56 formed on vertical arm 21 8 of guide member 260 in the overflow order (see also Fig. 18), and extends rearwardly and is offset into the next lower denominational order where it is adapted to overlie a pin I51 secured to the guide member 60 of that order. The lock piece I54 is normally maintained in its disengaged position of Figs. 5, 8 and 9 uder the tension of spring I58. Upon depression of minus key 86, however, and forward movement of link 255, the lever I48 is rocked in a clockwise direction urging the lock piece I 54 into engagement with pin I51 of the guide member 80 of the next lower order, where it is maintained until parallel motion bar 89 is released and allowed to rise to normal position. Upon engagement, therefore, of hook member 58 with toothed wheel 13 in the denominational order to the right of the overflow order, either resulting from setting of a digital key 24 therein and/or depression of the "equals control key 81 and release of lock arms I08 as already explained, the guide member 60 in that order will be pulled rearwardly and, by its connection with guide member 260 of the overflow order through the lock piece I54, the gear sector 242 of the overflow order will be given a maximum downward movement to add 9 upon its upward movement under the action of spring 246.

As the guide member of the overflow order is moved rearwardly as just described, pin 211 located in the upward extension of vertical arm 218 of the guide member 26!) engages finger 219 on the latch 266 to swing the latch member in a clockwise direction from its operative position of Fig. 6. The dog 261 is thus freed from am 215 of the latch 288 to allow parallel motion bar 89 to return to its normal raised position to remove tooth 9I from aperture 285 in the stem 88 of key 86. While this release of latch 288 will normally allow the associated spring 238 to return the minus key 86 to its upper or inoperative position, such operation cannot take place unless downward pressure has been removed from the equals key 81 and the latter has been returned to inoperative position by its spring 238 to remove the stem 88 thereof from the path of movement of the projection 93 on bar 92.

Means are provided for preventing the relatching in a depressed position of parallel motion bar 89 and minus key 86 if the "equals key 81 is allowed to rise while key 88 is still being held depressed by the operator, or if the "equals" key 81 is held down by the operator. To this end, there is provided a forwardly extending arm I58 on latch 266 of the overflow order which is adapted to engage the face of a lip or lug I8I formed at the extremity of a vertical lever I62 (as shown in Figs. 5, 6, 7 and 9). The lever I62 is moved slightly forward against the tension oi its spring I63 by the arm I59 when parallel motion bar 89 is depressed by the minus key 88, and link 255, to which the latch 286 is pivoted, is moved forwardly. Subsequent operation of the equals control key 81 causes rearward movement of the guide member 268 of the overflow order, as already described, whereupon pin 211 of guide member 260 engages the finger 219 of latch member 288 to swing the latter in a clockwise direction from its position of Fig. 6 to its position of Fig. 7. In such movement of the latch 288, the arm I59 thereof is swung beneath the lip or lug I8I on the lever I82, and the latter is moved rearwardly in a counter-clockwise direction by its spring I63 to maintain the latch 266 in inoperative position. In this position, the downwardly extending arm 215 of the latch 268 is to the rear of projection 216 of dog 281, and the dog cannot be relatched in such position until the parallel motion bar 89 has been allowed to return to its upper or normal position and has again been depressed by the "minus key 88. Thus the subtractive control devices are compelled to return to normal position after a subtractive operation, and the machine is automatically conditioned for additive operation.

Means are also provided to insure the proper sequence of depression of keys 86 and 81, respectively. This means comprises bar 82, earlier described, and its stop 93. In the normal or inoperative position of Fig. 5, stop 93 is directly beneath the lower surface of stem 88 of the equals" key 81 to effectively prevent depression of the equals key 81 before the minus key 86 is depressed. Upon depression of key 86, however, the bar 92 is moved rearwardly to the position of Fig. 6, due to its pivotal mounting upon the paral- 

